It is also meaningful to discuss whether VSOR Cl channel

2019-09-11

It is also meaningful to discuss whether VSOR Cl− channel-induced apoptosis is correlated with the ER pathway. Thus, in this study, we sought to clarify the intrinsic relationship between VSOR Cl− channels and the level of ER stress-related proteins. The research results are as follows: the expression of the GRP78 protein declines in CNE-2Z cells treated with GNA after 24 h, whereas the expression levels of the CHOP and ATF4 proteins increase. These data indicate that GNA may downregulate the expression of the ER stress-related protein GRP78 and upregulate the expression of the ER stress-related proteins CHOP and ATF4. GNA thereby contributed to the UPR protective mechanism and suppressed the anti-apoptotic effect of the UPR to induce apoptosis in the NPC cell line CNE-2Z. In contrast, DIDS and DCPIB upregulating the ER stress protein GRP78, downregulating the ATF4 protein, and blocking CHOP. DIDS and DCPIB clearly reduced the expression level of apoptosis factor CHOP, suggesting that the VSOR Cl− channel is engaged in ER stress-mediated apoptosis in CNE-2Z cells.
GNA induces apoptosis in CNE-2Z cells and activates VSOR Cl− Channel, accompanied by reduced GRP78 and elevated ATF4, CHOP proteins. DIDS and DCPIB un regulated the ER stress protein GRP78, down regulated the ATF4 protein, and blocking CHOP, linking with GNA-induced apoptosis.
Introduction
Haemonchus contortus is a pathogenic gastrointestinal parasitic nematode that causes severe livestock damage worldwide, particularly in the sheep industry. The disease, known as haemonchosis, leads to severe symptoms in host ruminants including anemia and death (Besier et al., 2016). Traditionally, H. contortus is controlled with broad spectrum anthelmintic chemotherapeutics that target different proteins within the parasite. There are multiple classes of these drugs that target cys-loop ligand-gated ion channels, including macrocyclic lactones which specifically target glutamate-gated chloride channels (GluCls) (Forrester et al., 2003; McCavera et al., 2009; Glendinning et al., 2011) and nicotinic Caspase-1, human recombinant proteinase mass receptor (nAChR) agonists such as pyrantel and levamisole (Boulin et al., 2011; Duguet et al., 2016; Blanchard et al., 2018). Macrocyclic lactones have also been shown to interact with nematode cys-loop GABA receptors (Accardi et al., 2012; Hernando and Bouzat, 2014). There is global concern about the increase in drug resistant populations of H. contortus in the field, including documented resistance to more recently developed drugs such as monepantel and derquantel (Raza et al., 2016). This information drives the need for the discovery of novel anthelmintic targets that could be used for the rational design or screening of new and effective anthelmintics.
The cys-loop ligand-gated chloride channel (LGCC) family of receptors is a very attractive group of proteins for drug-target discovery. Information from the H. contortus genome suggests that this family of receptors has approximately 35 genes that encode various subunits (Laing et al., 2013). However, approximately half of these potential channels have no confirmed ligand. In addition, many of these channels are either not present in mammals or are sufficiently divergent, suggesting the potential to develop highly specific drugs that will not target host receptors (Laing et al., 2013). However, of the 35 possible LGCC targets in the H. contortus genome it is likely that only a subset could be developed as targets for broad-spectrum anthelmintics. This is because the genomes of other parasitic nematodes, particularly human pathogens, appear to contain a significantly lower number of lgcc genes with some groups of channels being absent (Williamson et al., 2007; Beech et al., 2013). In addition, several LGCCs are likely to have functions that have no real consequence to the parasite if targeted. Therefore, the most attractive LGCCs from an anthelmintic discovery point of view are those present in a broad range of parasitic nematodes, have a function in the parasitic stage that if bound by an anthelmintic would lead to death or expulsion of the parasite and are not similar to host receptors (Wever et al., 2015). The latter point can be achieved by either targeting unique nematode-specific families of receptors or similar receptors that exhibit unique binding sites for potential drugs.